Abstract

RDFa Core 1.1 [RDFA-CORE] defines attributes and syntax for embedding semantic
markup in Host Languages. This document defines one such Host Language. This language
is a superset of XHTML 1.1 [XHTML11-2e], integrating the attributes as defined in RDFa
Core 1.1. This document is intended for authors who want to create
XHTML-Family documents that embed rich semantic markup.

Status of This Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

This is a revision of Sections 8 and 9 and Appendix A of RDFa Syntax 1.0 [RDFA-SYNTAX].
Once development is complete, if accepted by the W3C
membership, this document will supersede those sections of the previous
Recommendation. There are a number of substantive differences between
this version and its predecessor, including:

The inclusion of an implementation of the markup language using
XML Schema.

The addition of @lang to be consistent with recent
changes in [XHTML11-2e].

Deprecation of the use of @version.

Removed the collection of TERMs from this document - instead deferring the
definitions in a default RDFa Profile document.

A sample test harness is available. This set of tests is
not intended to be exhaustive. Users may find the tests to
be useful examples of RDFa usage.
An implementation report lists several implementations
of this specification tested during the Candidate Recommendation
period. A community-maintained Wiki page includes subsequent updates.

Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

1. Introduction

XHTML+RDFa 1.1 is an XHTML family markup language. It extends the XHTML 1.1 markup
language with the attributes defined in RDFa Core 1.1. The document also defines an
XHTML Modularization-compatible [XHTML-MODULARIZATION11-2e] module for the RDFa Core
attributes in both XML DTD and XML Schema formats.

2. Conformance

As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.

The key words must, must not, required, should, should not, recommended, may, and optional in this specification are to be interpreted as described in [RFC2119].

2.1 Document Conformance

A strictly conforming XHTML+RDFa document is a document that
requires only the facilities described as mandatory in this
specification. Such a document satisfies the following
criteria:

The start tag of the root element of the document must explicitly
contain a default namespace declaration for the XHTML namespace
[XML-NAMES11].
The namespace URI for XHTML is defined to be
http://www.w3.org/1999/xhtml.

The start tag may also contain the
declaration of the
XML Schema Instance Namespace and an XML Schema Instance
schemaLocation attribute [XMLSCHEMA-2]. Such
an attribute would associate the XHTML namespace
http://www.w3.org/1999/xhtml with the XML Schema at the
URI http://www.w3.org/MarkUp/SCHEMA/xhtml-rdfa-2.xsd.

Note that in this example, the XML declaration is included. An XML
declaration like the one above is
not required in all XML documents. XHTML document authors
should use XML declarations in all their documents.
XHTML document authors must use an XML declaration
when the character encoding of the document is other than the default UTF-8 or
UTF-16 and
no encoding is specified by a higher-level protocol.

XHTML+RDFa documents should be labeled with the Internet Media Type "application/xhtml+xml" as defined in [RFC3236]. For further information on using media types with XHTML family markup languages, see the informative note [XHTML-MEDIA-TYPES].

In the previous version of this specification, documents
could have used the @version attribute on the html
element as a way of announcing which version of XHTML+RDFa was in use.
That use of @version is no longer supported. A conforming
RDFa Processor must not use the value of @version to effect
its processing.

2.2 User Agent Conformance

A conforming user agent must support all of the features required
in this specification. A conforming user agent must also
support the User Agent conformance requirements as defined in XHTML Modularization
[XHTML-MODULARIZATION11-2e] section on "XHTML Family User Agent
Conformance".

3. Additional RDFa Processing Rules

Documents conforming to the rules in this specification are processed
according to [RDFA-CORE] with the following extensions:

The default vocabulary URI is undefined.

The default collection of terms is defined in via an
RDFa Profile document at
http://www.w3.org/1999/xhtml/vocab.

In section 6.5, processing step 6, if no URI is provided by a resource attribute, then
first check to see if the element is the head or
body element. If it is, then act as if there is an empty @about present,
and process it according to the rule for @about.

In section 6.5, processing step 7, if no URI is provided, then
first check to see if the element is the head or
body element. If it is, then act as if there is an empty @about present,
and process it according to the rule for @about.

4. XHTML+RDFa 1.1 Definition

The XHTML+RDFa 1.1 document type is a fully functional document type
with rich semantics. It is a superset of [XHTML11-2e].

The XHTML+RDFa 1.1
document type is made up of the following XHTML modules. The elements,
attributes, and content models associated with these modules
are defined in "XHTML Modularization" [XHTML-MODULARIZATION11-2e].
The elements are listed here for information purposes, but the
definitions
in XHTML Modularization should be considered authoritative.

This specification also adds the lang attribute to the I18N
attribute collection as defined in [XHTML-MODULARIZATION11-2e].
The
lang attribute is defined in [HTML401].
When this attribute
and the xml:lang attribute are specified on the same element, the
xml:lang attribute takes precedence.
When both lang and xml:lang are
specified on the same element, they must have the same value.

There are no additional definitions
required by this document type. An implementation of this document type as an
XML Schema is defined in
Appendix A, and as an
XML DTD is defined in
Appendix B.

5. Metainformation Attributes Module

The Metainformation Attributes Module
defines the Metainformation attribute collection
in the format required by [XHTML-MODULARIZATION11-2e].
This collection allows elements to be annotated with metadata
throughout an XHTML-family document. When this module is included
in a markup language,
this collection is added to the Common attribute
collection as defined in [XHTML-MODULARIZATION11-2e].

5.1 Metainformation Attributes Collection

The following attributes are included in the attribute collection, and
take values in the associated datatype:

A URI that defines the prefix to use when a CURIE is specified with no prefix
and no colon.

An implementation of this module in XML Schema can be
found in Appendix A and in
XML DTD in Appendix B.

5.2 XHTML Default RDFa Profile

This section is non-normative.

This specification provides a default RDFa Profile. It
is available at http://www.w3.org/1999/xhtml/vocab.

A. XHTML+RDFa XML Schema

This appendix is normative.

This appendix includes an implementation of the
XHTML+RDFa 1.1 language using XML Schema.
It is implemented by combining the XHTML 1.1 Schema
with the XHTML Metainformation Attribute Module.
This is done by using
a content model module, and then a driver module.
There are direct links to the various files, and the files
are also contained in the "Gzip'd TAR" and "Zip" archives linked to at the
top of this document.
Please note that the files targeted by the "latest version" links may
change slowly over time. See the
W3CXHTML2 Working Group home page for more
information.

B. XHTML+RDFa Document Type Definition

This appendix includes an implementation of the
XHTML+RDFa 1.1 language as an XML DTD.
It is implemented by combining the XHTML 1.1 DTD
with the XHTML Metainformation Attribute Module.
This is done by using
a content model module, and then a driver module.
There are direct links to the various files, and the files
are also contained in the "Gzip'd TAR" and "Zip" archives linked to at the
top of this document.
Please note that the files targeted by the "latest version" links may
change slowly over time. See the
W3CXHTML2 Working Group home page for more
information.

C. Deployment Advice

This section is non-normative.

Documents written using the markup language defined in
this specification can be validated using the
DTD defined in Appendix B. If a document author wants
to facilitate such validation, they may include the following
declaration at the top of their document:

The XML Namespace document associated with the
XHTML Family of markup languages uses the
mechanism for transforming XHTML+RDFa documents into
RDF as defined by [GRDDL].
Authors who want to be certain their documents are
transformable by all [GRDDL] processors may
also include a profile attribute on the
head element that includes a
reference to the XHTML vocabulary URI
http://www.w3.org/1999/xhtml/vocab.

D. Change History

This section is non-normative.

2010-02-25: First version of the split-out XHTML specialization.

E. Acknowledgments

This section is non-normative.

At the time of publication, the members of the
RDFa Working Group were:

Ben Adida, Creative Commons (Co-Chair)

Benjamin Adrian, German Research Center for Artificial Intelligence (DFKI) Gmbh